Ringer circuit



Dec. 7, 194s. Q A, SHANN 2,455,386

l Rmenn CIRCUIT Filed Dec. 6, "1944 /NL/E/v To@ O. A. SHANN from/EV A Patented Dec. 7, 1948 RINGER CIRCUIT @scar A. Shann, Short Hills, N. J., assignor to Bell rlelephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application December 6, 1944, Serial No. 566,807

7 Claims.

This invention relates to telephone systems and particularly to arrangements for calling subscribers lines.

An object is to improve the method and apparatus for calling subscribers lines.

Heretofore various systems have been used in which a subscriber is called by operating the called subscribers bell in different manners. For example, the bell may be operated with a gradually increasing sound intensity either by mechanical damping means applied to the bell or by arrangements for gradually increasing the frequency of the operating intervals of the bell.

It is `a feature of the applicants invention to provide a ringer at a substation having tap gongs and automatic switching means at the central oice operative on the seizure of the called subscribers line for actuating the ringer to tap the gong once and if the subscriber does not answer this call within a certain interval thereafter, for actuating the ringer to tap the gong repeatedly at shorter intervals.

The invention has been illustrated in the accompanying drawing.

Referring now to the drawing, the invention is shown applied to an automatic ltelephone system. A calling subscribers station is shown at I, with la connection through a switch 2 illustrated merely by brushes and contacts to a connector, or line connection initiating, circuit 3 having access to a called subscribers station 4. The connector cir-cuit 3 is merely shown with such parts of the circuit as are oi particular interest in connection with the applicants invention as applied thereto.

At subscriber-s station il is shown a ringer 5 having a self-interrupting contact -6 and an armature to which is connected a clapper 8 for tapping th-e gong 9.

The operation of this system is as follows: If l a calling subscriber I establishes a connection through switch 2 to Iconnector circuit 3, the lconnector circuit which may be of any well-known type establishes through equipment indicated merely by box I l), a connection for the operation of relay II through its upper winding. This operation takes place vas is well known in connector circuit practice, when the brushes I2 have been actuated by a series of impulses to establish a connection 'to the terminals I3 of the line leading to the called subscribers station 4. Thus when relay I I operates a locking circuit for maintaining itself operated is established from battery, through the lower winding, the lower inner armature and front contact of relay II to a ground (not shown) in the circuit arrangement I0, and

a. connection to ground is also established through the lower outer armature and front -contact to the sleeve terminal of the line l2 to make this called line busy. An immediate other effect of the operation of relay I I is that a circuit is established for the operation of ringer 5 in a circuit traceable from battery I4, contacts of relays I5 and II, upper winding and contacts of relay I6, contacts of relay I I, the ring brush 'and terminal of the called line, windings of ringer 5, armature 1, contact 6, tip terminal and brush, contacts oi relays II and I6 to ground. This circuit, upon closing, does not operate marginal relay I6 when the circuit first closes but does cause the windings of ringer 5 to attract the armature 'I. Armature l, upon operating, (1) causes clapper 8 to tap the gong 9 once, (2) interrupts this circuit and (3) permits current from battery I4 to flow through the element I1 which is of the type having a negative temperature coeicien-t of resistance. The voltage of battery I4 now causes a decrease in resistance of element I'I due to these characteristics yand thus increases the current to maintain the ringer operated with armature 1 attracted. Thus clapper 8 will -only tap gong 9 once to call the called subscriber.

If the called subscriber does not answer this signal within a certain period of time, the following operations will take place. It should be noted that upon the operation of relay I I, a circuit was completed for operation of the slow-to-operate relay 2U which circuit is traceable from battery, through the winding of relay 20, contacts of relays I5 and II, to ground. Relay 20, in operating, closes an obvious circuit for slow-to-operate relay 2I and this relay, in operating, closes an obvious circuit for slow-to-operate relay I5. When relay I5 finally operates depending on the time it takes to operate relays 2l), 2| and I5, the direct connection from battery I4, through the upper armature and back contact of relay I5 maintaining ringer 5 operated, is opened and a connection is established from battery I4, through a resist- `ance 23 and the upper armature and front contact of relay I5 over the circuit hereinbefore traced through element I'I and ringer 5. The presence of resistance 23 in this circuit causes relement I1 to be subjected to a lower voltage and hen-ce to increase its resistance sufficient to permit ringer 5 to release the armature 'I to close a circuit through its back contact '6. When this takes place element I'I will be shunted :and the ringer will Aagain operate and open the connection Ithrough armature I and its back contact 6 and these operations will be repeated as in any self-interrupting or buzzing circuit for a relay independent of element Il. Relay I5 selves -to switch resistance 23 into the terminating connector circuit at a predetermined interval of time after the single tap on the gong. Thus clapper 8 will repeatedly tap gong 9 at a corresponding frequency or rate and thus this continued tapping of the gong will urge the subscriber -to lanswer the call. Then when the subscriber at the called station Il answers, a shunt circuit for ringer 5 is established across the tip and ring conductors and the telephone set, from the tip terminal, .the right-hand winding of repeating coil 2G, switchhook 21, a transmitter 28, contacts of dial 29, the ring terminals and across the :tip "and ring brushes I2. This circuit will now exten-d from battery I4, resistance 23, contacts -ofrelays I5 and II, the upper winding of marginal relay I6, the lower outer armature and back contactof-this relay, contacts of relay il, to the ring conductor and through .the above-mentioned circuit at the calling subscribers substation-4, contacts Iof relaysfI'I vand I6 to ground. When ringer 5 and element l1 are 'sh-tinted -by the circuit just traced, marginal relay I6 operates `to extend the connection from the called subscribers line over the tiprand vring conductors through contacts of relays 'Il and i6, to the battery and ground through the respective windings of relayk llvwhich operates.

Relay 30, upon operating, closes a holding circuit ,Y

for relay I6 which, in its voperated position, completes the talking circuit between the 4called subscribers line 4and the calling subscribers line over condensers 43l as is usual in connector circuitsof this kind. ina .similar manner relay 30, upon operating, provides da holding circuit for relay II which is locked Ioperated from ground (not shown) in circuit arrangement IG. It should be noted that upon the operation of relay `I5,g1oc1 ing circuit was provided tor this relay, extending from battery, through the lower winding and its lower inner armature and iront contact, to ground at contacts of relay il so that :thisrelay is maintained operated as long as relayjIIV is operated. When `relay I5 loperated, relay 20 was released, and this in turn caused the release of relay 2I. Now, therefore, as long 'as relay I'I is operated relay'I is main-tained actuated. However, the circuit extending from'battery Il! and resistance -23 to the upper armature and front contact of relay i5 is broken upon the operation of relay I6 at the lower outer armature and back contact of relay l5 but relay I5 is heldoperated, as "hereinbefore stated, `in a circuit extending from battery, through its lower winding, lower inner amature and front contact to ground at contacts of relay 30, ,When the called subscriberdisconnects, relay 30 releases Vto thereby release relay I6 and when the calling subscriber` disconnects, relay I l releases to thereby release, in turn, relays 30 land I6, relay-3i) releasing, if it has not already been released. When the calling subscriber disconnects, connector 3 is released tonormal.. The releaseof relay I I causes release of relay AI 5.

VVliat is claimed ist l. In a telephone system, lines, subscribers station apparatus connected thereto and including ringers having tap gongs, automatic switching means for establishing a connection from a calle ing station to a called station, impedance means eectively cooperative upon the seizure of one of said -lines in operating the associated ringer to .ta-p the gong once, and other impedance means effectivelycooperative if the subscriberat the station of the called line does not .answer Within a once, and other impedance means eiectively cooperative, -a predetermined interval thereafter, in

'causing the first-mentioned impedance means to automatically increase its resistance value whereby the ringer is actuated to tap the gong repeatedly at shorter intervals.

3. In a ringer operating system, a ringei` having sel-interruptingcontacts, a negative resistance elementshunting the self-interrupting contacts of said ringer and circuit means for establishing a connection through the ringer and said element to affect said element so as to cause said ringer to operate once only and another circuit means -for establishing a denite interval after said operation of the ringer, a connection through the vringer and said element to effect repeated operationsof the ringer under control of the selfinterrupting :contacts .and to prevent the element from interfering with said repeated operations.

4. A ringer operating system comprising a ringer having gongs and an armature having a clap-per tortapping said gongs when the ringer is actuated to attract said arma-ture, a circuit for ,said ringer, yan element having negative resistance characteristics in said circuit, a resistance, means for including in said circuit said resistance to prevent said negative resistance element from interfering with the continuous operation and release of said armature to permitsaid clapper to repeated'ly tap on said gongs, and means for excluding from said circuit said resistance to permit said negative resistance. element to function in said circuit to operate the armature once to cause said clapper to tap-said gongs with a single stroke.

A5. A ringer operating system comprising a ringer having a gong, an armature for actuating said gong each time the armature is attracted on the energization of the winding of said ringer, normally closed contacts opened by said armature when attracted, an element having negative resistance characteristics connected in shunt with said contacts, a source of current, a resist-ance, a circuit through said winding and contacts, a switch for closing said circuit through said winding, said contacts and source of current to energize said winding to attract the armature to operate the gong and to open said contacts, the resistance of said element being of such value as to permit said winding to remain sufficiently energizedto maintain the armature attracted and said contacts `opened after the armature has operated the gong once onlyand another switch for closing said circuit through said winding, said contacts, source of current .and resistance to energize said winding to attract the armature to operate the gong .and to open said contacts, said resistance and said `element being of such value as to permit the repeated operation and release of said armature land .the opening and closing of said contacts for the actuation of said gong on each attraction of said armature.

,6. A ringer operating system comprising a ringer having self-interrupting contacts, an element having negative resistance characteristics shun-ted across said contacts, a resistance, a source of current, switching means and circuit connections to first establish a connection through said element, and said self-interrupting contacts and Winding of said ringer from said source of current and after an interval to include in said circuit connection said resistance in series with the source of current, said source of current being so adjusted that cn the rst operation of said switching means a resulting high voltage in said circuit connection permits said element to decrease its resistance to cause said ringer to operate once only and said resistance being so adjusted in relation to said source of current that on the subsequent operation of said switching means -a resulting lov7 voltage in said circuit connection permits lthe element `to remain at a high resistance and thus cause said ringer to alternately operate and release under control of the self-interrupting contacts.

7. A ringer operatingr system comprising 'a line connection initiating circuit, a ringer having a gong, an armature provided with -a clapper for striking the gong on the operation of the armature, self-interrupting contacts controlled by the armature, an element having negative resistance characteristics, terminals, a circuit extending from one terminal to said contacts and said element, in parallel, through the winding of said ringer to the other terminal, a connector switch circuit having brushes for establishing connections to said .terminals upon the operation of said connector switch, a relay in said connector switch circuit having an armature, a back Contact normally connected to said armature and a front 4contact normally disconnected from said armature, a source of current in said connector switch circuit connected to said back contact, -a resistance connected between said source of current and said front contact, means controlled by said line connection initiating circuit responsive to the operation thereof ior connecting saidl source of current at said contacts and said arm-ature of said relay, in a path extending through said brushes and terminals and through said element and selfinterrupting contacts of said ringer, in parallel, through the winding of said ringer to ground for the operation of -said ringer to attract its armature to strike said gong with said clapper and to open said self-interrupting .contacts controlled by the ringer armature and thereby cause said element to reduce its resistance to permit the ringer to remain operated, and further means -controlled by said line connection initiating circuit for thereafter operating said relay after an interval of relatively long duration to open the connection at sai-d back contact and lclose the connection tat said front contact for the connection of the resistance, in series, with the source of current in a -circuit eXtending through said relay armature, through the winding of said ringer and through said element, in series, to permit said element .to increase the resistance accordingly so that said ringer will thereafter alternately release and operate under control of said self-interrupting contacts for the repeated striking of the gong by the clapper at a speed depending on the magnetic characteris-tics of said ringer and the impedance characteristics of said element.

OSCAR A. SHANN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,352,081 Moran ISept. '7, 1920 2,151,726 Allen Mar. 28, 1939 2,260,524 Hersey Oct, 28, 1941 2,332,448 Inglis Oct. 19, 1943 

